Electric discharge lamp



lrwen kor. Edward E MiLes, b W His Attorneg.

E. E. MILES ELECTRIC DISCHARGE LAMP Filed July 8 1949 Feb. 20, 1951 Patented Feb. 20, 1951 ELECTRIC DISCHARGE LAMP Edward Ernest Miles, Wembley, England, assignor to General Electric Company, a corporation of New York Application July 8, 1949, Serial No. 103,552 In Great Britain August 16, 1948 2 Claims. (Cl. 176-122) This invention relates to methods of and means for attaching a vitreous surface to a metal surface or to another vitreous surface, for uses when the joint is not required to withstand high temperatures, for example greater than 100 (2., and is more particularly, but not exclusively, concerned with methods of and means for attaching a thin metal conductor to the exterior surface of the glass envelope of a tubular electric discharge lamp. Such thin conductors, usually in the form of a wire or strip, are used for facilitating starting of the lamp and the secure attachment of the conductor to the glass envelope has hitherto presented considerable difficulty.

The object of this invention is to provide a novel adhesive for such purposes with which very satisfactory joints can be obtained.

According to the invention, a method of attachins. a vitreous surface to a metal surface or to another vitreous surface for use where the joint is not required to withstand high temperatures, is characerized by the use as adhesive of polyethylene, especially as sold under the trade name Polythene.

Preferably the polyethylene is placed in solid form between the two surfaces to be joined, the polyethylene is then heated so as to render it plastic or liquid, and the two surfaces are pressed together so that the polyethylene adheres to both and forms a solid joint between them on cooling.

The heating of the polyethylene may be effected by means of heat communicated to it from one or both of the surfaces to be joined, which may be preheated for the purpose.

In the case of the attachment of a thin metal starting conductor to the glass envelope of an electric discharge lamp, the conductor may be embedded in polyethylene by placing a layer of polyethylene on the conductor as well as between the conductor and the glass surface. The polyethylene may be heated by preheating of the glass envelope and the joint formed by pressing the conductor and layers of polyethylene against the glass by means of a roller run along the length of the conductor. If desired, the roller may also be heated, or a heated roller may be used as an alternative to heating of the glass.

If the conductor consists of a wire or strip, it is preferably preformed with a sheath of polyethylene, which preforming may be by an extrusion process or by spraying the metal wire or strip with polyethylene or by pressing two layers of polyethylene onto the metal wire or strip by means of a heated roller. Thus, in carrying out 2 the method in accordance with the invention, a suitable length cut from a reel of polyethyleneclad wire or strip may merely be placed along the preheated class envelope and attached to it by running a roller along the length of the wire or strip so as to press it against the heated glass.

One method of attaching a thin metal starting strip to the glass envelope of an electric discharge lamp without the use of precoated strip will now be described in detail by way of example in connection with the drawing wherein Fig. 1 is an elevation, partly in section, showing the applcation of the adhesive to the strip, Figs. 2 and 3 are similar views showing application of the strip to the envelope, and Fig. 4 is a side elevation, partly in section, of a completed lamp.

In this example, the metal strip l consists of a nickel tape approximately 0.5 mm. wide and 0.03 mm. thck and the glass envelope 2 is approximately 38 mm. in external diameter. As shown in Fig. 1, the nickel tape I is first embedded between two strips of polyethylene 3.3. each about 1 mm. wide and 0.1 mm. thick, by placing the three strips one upon the other and pressing them together by means of a heated roller 4.

The envelope 2 (Fig. 2) is then heated in a suitable furnace and a strip of the polyethylenecovered nickel tape I is quickly placed on the outer surface of the lamp envelope parallel to the lamp axis and pressed firmly onto the hot envelope by means of a roller 5, after which the envelope is allowed to cool with the strip attached thereto as shown in Fig. 3.

The completed lamp is shown in Fig. 4 and comprises the envelope 2 which contains an ionizable medium. preferably a filling of a rare gas like argon or krypton at a pressure of a few millimeters and a small amount of mercury which during operation of the lamp may have a vapor pressure of the order of 10 microns. The envelope 2 may be coated internally with fluorescent powders. The lamp also contains electrodes I, 8 at the ends of the envelope which may be of the activated filamentary type and connected to pairs of contacts on the metal end caps or bases I, I. The ends of the nickel tape I may be attached to the said bases 1, 'i if desired.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A gaseous electric dischar e device comprising a vitreous envelope containing an ionizable medium, and a thin metallic conductor attached to said envelope by an adhesive consisting of polvethylene.

2. A gaseous electric discharge device compris- 3 in; a vitreous envelope containing an ionizable medium, and a thin metallic conductor embedded in and attached to said envelope by an adhesive consisting of polyethylene.

EDWARD ERNEST MILES.

file of thls'pe-tent:

Number UNITED STATES PATENTS Name Date Freitag Oct. 5, 1937 Randall Nov. 8, 1938 Fawcett Oct. 29, 1940 Child Feb. 1, 1944 But! Feb. 22, 1949 

1. A GASEOUS ELECTRIC DISCHARGE DEVICE COMPRISING A VITREOUS ENVELOPE CONTAINING AN IONIZABLE MEDIUM, AND A THIN METALLIC CONDUCTOR ATTACHED TO SAID ENVELOPE BY AN ADHESIVE CONSISTING OF POLYETHYLENE. 